Adjacent counties

Big Horn County in Wyoming and Montana are one of ten pairs of counties and parishes in the United States with the same name to border each other across state lines. The others are Sabine (Texas and Louisiana), Union (Arkansas and Louisiana), Bristol (Massachusetts and Rhode Island), Kent (Maryland and Delaware), Escambia (Alabama and Florida), Pike (Illinois and Missouri), Teton (Idaho and Wyoming), Park (Montana and Wyoming), and San Juan (New Mexico and Utah - albeit through a single point, the four corners).

Major highways

Transit

• Express Arrow

National protected areas

• Bighorn Canyon National Recreation Area (part)
• Bighorn National Forest (part)

2000 census

As of the 2000 United States Census,^[10] there were 11,461 people, 4,312 households, and 3,087 families in the county. The population density was 4 people per square mile (1.5 people/km²). There were 5,105 housing units at an average density of 2 units per square mile (0.77 units/km²). The racial makeup of the county was 94.03% White, 0.11% Black or African American, 0.75% Native American, 0.21% Asian, 0.07% Pacific Islander, 3.37% from other races, and 1.46% from two or more races. 6.17% of the population were Hispanic or Latino of any race. 23.0% were of German, 21.4% English, 8.1% American and 8.0% Irish ancestry.

There were 4,312 households, out of which 32.50% had children under the age of 18 living with them, 61.00% were married couples living together, 6.80% had a female householder with no husband present, and 28.40% were non-families. 25.00% of all households were made up of individuals, and 11.90% had someone living alone who was 65 years of age or older. The average household size was 2.60 and the average family size was 3.13.

The county population contained 28.70% under the age of 18, 7.30% from 18 to 24, 22.60% from 25 to 44, 24.60% from 45 to 64, and 16.80% who were 65 years of age or older. The median age was 39 years. For every 100 females there were 100.20 males. For every 100 females age 18 and over, there were 97.10 males.

The median income for a household in the county was $32,682, and the median income for a family was $38,237. Males had a median income of $30,843 versus $19,489 for females. The per capita income for the county was $15,086. About 10.20% of families and 14.10% of the population were below the poverty line, including 19.20% of those under age 18 and 10.00% of those age 65 or over.

2010 census

As of the 2010 United States Census, there were 11,668 people, 4,561 households, and 3,179 families in the county.^[11] The population density was 3.7 people per square mile (1.4 people/km²). There were 5,379 housing units at an average density of 1.7 units per square mile (0.66 units/km²).^[12] The racial makeup of the county was 94.4% white, 0.9% American Indian, 0.3% Asian, 0.2% black or African American, 3.0% from other races, and 1.2% from two or more races. Those of Hispanic or Latino origin made up 8.4% of the population.^[11] In terms of ancestry, 30.0% were German, 22.3% were English, 10.4% were Irish, 7.6% were Scottish, and 5.7% were American.^[13]

Of the 4,561 households, 31.0% had children under the age of 18 living with them, 58.2% were married couples living together, 7.6% had a female householder with no husband present, 30.3% were non-families, and 26.2% of all households were made up of individuals. The average household size was 2.52 and the average family size was 3.05. The median age was 41.8 years.^[11]

The median income for a household in the county was $48,270 and the median income for a family was $57,705. Males had a median income of $40,762 versus $31,440 for females. The per capita income for the county was $24,486. About 5.7% of families and 8.9% of the population were below the poverty line, including 11.2% of those under age 18 and 7.1% of those age 65 or over.^[14]

Towns

Census-designated places

• Hyattville
• Shell

Unincorporated communities